Poland, December 1945.

A Polish nun asks Mathilde Beaulieu, a young Red Cross intern in charge of caring for French survivors before they are repatriated, to help her.

 At first reticent, Mathilde finally accepts to follow the nun to her convent, where thirty Benedictine nuns live cut off from the world. She discovers that several of them who had been raped by Soviet soldiers are due to give birth.

Little by little, complex relationships form between Mathilde, an atheist and rationalist, and the nuns, commited to the rules of their vocation, which danger, the clandestinity of the treatment, and new dramas will complicate even further.